Triple X syndrome
also called
Trisomy X
rarechromo.org
Triple X syndrome or Trisomy X
Triple X syndrome (Trisomy X) is a genetic condition that only affects females. Girls and
women with triple X syndrome have an extra X chromosome.
Most people have 46 chromosomes, made up of tightly coiled DNA along which are the
genes that instruct the body to develop and work properly. There are twenty-two pairs of
chromosomes numbered 1 to 22 plus two sex chromosomes. In males the sex
chromosomes are different: one is called X and one is called Y, so male chromosomes
are usually described as 46,XY. Females usually have two X chromosomes and are
described as 46,XX. Females with triple X syndrome have an extra X chromosome, so
three in all. Triple X syndrome is sometimes called 47,XXX.
We suggest that you use the full name Triple X syndrome as a search term on
the internet. Alternatively, use Trisomy X.
How common is Triple X syndrome?
Around one girl in 1,000 has triple X syndrome.
Based on this figure, in 2013 around 3½ million
girls and women in the world are estimated to have
an extra X chromosome. The great majority of them
- perhaps 90% - never know that they have this
extra chromosome. In the United Kingdom an
estimated 31,800 females have triple X syndrome.
In the US, an estimated 158,500 girls and women
have triple X syndrome. In Australia around 11,600
females have triple X syndrome. When this
information guide was written, Unique had over 137
members with triple X syndrome, aged from birth to
66 years old. There are other internet-based
support groups specific to triple X syndrome. Some
of them are listed on the back of this information
guide.
Mosaic Triple X syndrome
Most women and girls with triple X syndrome have one extra X chromosome in the cells
of their body. But quite a few girls and women have some cells with three X
chromosomes and some with a different number of X chromosomes. This is known as
mosaicism. Mosaicism can change the effects of triple X syndrome.
These are the most frequent types of triple X mosaicism:
47,XXX/46,XX - Generally speaking, the effects of triple X will be milder, lessened by the
presence of cells with the normal number of X chromosomes in some tissues of the body
45,X/47,XXX - This is essentially a mosaic form of Turner syndrome (TS), although the
presence of cells with an extra X chromosome will generally moderate the TS features,
especially if the ratio of 47,XXX cells to 45,X cells is high
47,XXX/48,XXXX Generally speaking, a girl or woman with this chromosome make-up will
show aspects of both triple X syndrome (47,XXX) and tetrasomy X (48,XXXX). But as there
is great variation in people with both conditions, girls and women with this form of
mosaicism will also show a lot of variation. Unique has a separate guide to tetrasomy X.
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Information about Triple X syndrome
We know about triple X syndrome from
studying girls and women who are known
to have an extra X chromosome. In the
1960s almost 200,000 newborn babies from
six centres worldwide had their
chromosomes checked and those with
triple X syndrome were followed up, in
some places for more than 20 years. These
girls and women are the source of most of
what we know about triple X syndrome.
The information from studying these girls
as they grew up is unbiased because they
were not diagnosed because they had
problems. However, the numbers of girls
followed up, especially into adulthood, are
very small. For instance, in the Edinburgh
centre only 16 women with triple X
syndrome were still being studied by 1999.
Social conditions have also changed a lot
since the 1960s.
Today, there are two ways that the extra
chromosome is usually discovered.
A pregnant woman has an amniocentesis,
usually because she is an older mother:
information from this group is also unbiased.
A baby, girl or woman is investigated because of development or health problems:
information from this group is skewed towards abnormality. It doesn’t show a fair picture
of how triple X syndrome generally affects girls and women. But this information can still
be helpful to families.
Sources
The information in this guide comes from the medical literature, from a recent study in
the United Kingdom on the development of children with an extra sex chromosome
(DIESC study), from Unique and from a survey of 43 families diagnosed before birth by the
UK Triple X syndrome support group in collaboration with the late Dr Shirley Ratcliffe, in
her time an authority on sex chromosome anomalies.
References
The text contains references to articles in the medical literature. The first-named author
and publication date are given to allow you to search for the abstracts or original articles
on the internet in PubMed (www.ncbi.nlm.nih.gov/pubmed). If you wish, you can obtain
articles from Unique. The guide refers particularly to A review of trisomy X (47,XXX) by Dr
Nicole Tartaglia and colleagues and published in the Orphanet Journal of Rare Diseases
in 2010 (doi: 1186/1750-1172-5-8). This is an invaluable and comprehensive guide and is
available to everyone on the internet via PubMed. The guide also refers to Triple X
syndrome: a review of the literature by a psychiatrist, Dr Maarten Otter and his
colleagues and published in the European Journal of Human Genetics in 2009
(doi:10.1038/ejhg.2009.109) (Otter 2009).
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Typical features of Triple X syndrome
Triple X syndrome affects individual girls and women differently. Some are scarcely
affected, if at all, while others can have obvious and significant problems. These are the
most typical features:
•
•
•
Speech delay
•
Vulnerability to difficulties in making
friends at school age, normalising in
adolescence
•
Increased vulnerability to behavioural
and social stress
•
Mild delay in physical development
Need for some extra learning support
Rapid growth at 4-13 years, with
especially long legs
What causes Triple X syndrome?
In most cases it’s not known what causes triple X syndrome. Girls usually inherit one X
chromosome from their father and one from their mother. Girls with triple X syndrome
can inherit their extra X chromosome from either parent but it’s more common from
their mother. Early studies showed that the average age of the mother of a baby with
triple X syndrome is 33, which is higher than average (Otter 2009). Even so, most babies
with triple X syndrome are born to younger mothers.
When eggs form, chromosome pairs usually divide so that each cell has a single X
chromosome. Mistakes during cell division can leave two X chromosomes in the egg cell.
This type of mistake is known as non-disjunction. Fertilised by a single X-carrying sperm,
the egg will then develop into a baby with three X chromosomes.
In around one fifth of all cases, a mistake occurs just after fertilisation during the copying
of the early cells that will become an embryo, then a fetus and then a baby (Tartaglia
2010).
Egg cells
Cell with no
Cell with extra
X chromosome
Normal cells with
one X chromosome
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Was it my fault?
No. Triple X syndrome is a random event. No environmental, dietary, workplace or
lifestyle factors are known to cause sex chromosome variations such as triple X
syndrome. There is nothing you did before you were pregnant or during pregnancy that
caused triple X syndrome to occur and there is also nothing you could have done to
prevent it.
Diagnosis
Most girls and women with triple X syndrome never know that they have an extra X
chromosome. When it is found, in pregnant women, the extra X chromosome is usually
discovered during prenatal tests for other chromosome disorders such as Down’s
syndrome.
The extra X chromosome is sometimes found after birth when chromosomes are
examined because of concern about a girl’s unusual physical features or development. In
girls with triple X syndrome, the signs may be so subtle that the diagnosis is reached late.
Outlook
Most girls and women with triple X syndrome lead normal lives. They go to mainstream
schools, have jobs and children and live into old age.
There are certain differences between girls with triple X syndrome and girls with two X
chromosomes. Most of the differences are what you would find as part of normal
variation between individuals.
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Babies
Babies with triple X syndrome usually look perfectly normal at birth with nothing to
suggest the extra X chromosome. A typical baby with 47,XXX weighs on average 3kg (6lb
10oz), that is 400-500g (14-18oz) less than a baby with two X chromosomes. Typically, the
head is a little smaller than average (Otter 2009). The tone of the muscles may be slightly
low so the baby feels rather floppy to hold.
On average, babies smile at two months, with the earliest smiling at one month and the
latest at six months (Triple X syndrome group 2006). Most babies are breastfed and in a
survey by the Triple X syndrome group none needed tube feeding.
On the move
Girls with triple X syndrome may be a little late starting to crawl and taking their first
steps. But there’s a huge variation between individuals. Girls with triple X syndrome
typically crawl around 10 months (range five - 20 months) and take their first steps
around 16-18 months but the known range is nine to 36 months (Triple X syndrome group
2006; Tartaglia 2010). Despite any initial delay, by school age, many girls with triple X
syndrome are taking part in sports and team sports (DIESC 2009; Linden 2002;
Pennington 1980).
Underlying the slight delay are motor coordination problems in many (Otter 2009) and
continuation of low muscle tone and bendy joints in some (Triple X syndrome group 2006;
Tartaglia 2010). Among 24 children aged 0-5, a quarter of the girls had low muscle tone,
affecting different parts of the body. Of four children with unusually bendy joints and low
muscle tone, three were late walkers, taking their first steps after 18 months. Among a
group of 25 girls aged 6-10, ten had hypotonia (low muscle tone), again affecting different
parts of the body. In the 11-16 age group, 3/17 girls had slack abdominal muscles, giving
them a protruding stomach (Triple X syndrome group 2006). Other studies have shown
that as a group, girls are more easily tired (Otter 2009).
Girls on
the move
top left
at 5 years
bottom
left at 9
years
centre
at 7 years
right
at 11
years
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Some difficulties with planning movements have been observed and these may create
problems in complex muscle sequences such as those needed for sport. All the same,
girls generally find that both gross motor (movement) and fine motor (hand-eye)
coordination appear to be well preserved (DIESC 2009; Otter 2009; Salbenblatt 1989).
Further, some studies have reported well-preserved fine motor coordination with good
sensory motor integration (Linden & Bender 2002; Salbenblatt 1989; Robinson 1990).
Twenty-five per cent of families told the DIESC researchers that their daughter was good
at sport. Families told the researchers that if their daughters persevered with activities,
they built up muscle strength and enjoyed activities such as swimming, dancing and
horse riding. Nonetheless, girls found both fine and gross motor skills more difficult than
their siblings did. Their handwriting may be messy or they may be uncoordinated or
clumsy when using cutlery.
Everyday behaviours
Many girls with triple X syndrome take longer than average to be potty trained. They
achieve this on average around 36 months (range 12 months to 10 years) with the great
majority clean and dry by four years. Night-time dryness emerges typically in the fourth
year, on average by 44 months, but the range is broad, from 18 months to over six years
(Triple X syndrome group 2006).
Sixteen years old
The DIESC study found that girls with triple X syndrome were as good as their sisters at
understanding money, time and play and leisure skills (DIESC 2009).
Girls with triple X syndrome find many everyday tasks a little more difficult than their
siblings but still perform within the expected range for their age.
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Learning to talk
Girls with triple X syndrome are typically a little slow to start speaking but still achieve
within the expected range for their age. Typically, they say their first words around or
shortly after their first birthday and their first sentences at or around their second
birthday.
Around half of girls show a delay in both understanding and speech and three-quarters of
school-age girls have some difficulty with language. Studies suggest that 40-90 per cent
of girls benefit from speech therapy. The best age to start speech therapy isn’t certain,
but some say the earlier the better as early intervention can do no harm and may do
some good (Linden 2002; Triple X syndrome group 2006; Otter 2009; Tartaglia 2010).
Girls can find it difficult to retrieve words whether they are
under a time constraint or not. Compared with their brothers
or sisters, they use less complex syntax at a similar age and
have a narrower grasp of meaning. Other aspects of
communication, such as interests and non-verbal
communication, appear to be unaffected by the extra X
chromosome. The DIESC study found that girls with 47,XXX
seem to find structural aspects of language more difficult,
such as expressing themselves or understanding complex
sentences. They didn’t have particular difficulties with
aspects of language such as when to say things
appropriately, taking turns and so on.
Five years old
Families report that their daughters are chatty but have a
slightly more limited vocabulary than their siblings (DIESC
2009). Among 25 girls aged 6-10, almost half had speech
delay. Out of 17 girls aged 11-16 only two were still receiving
speech therapy (Triple X syndrome group 2006).
Families at a Unique study day said that singing, repetition and music with a beat help
speech. Some said that their daughters were hypersensitive to loud noises (Unique).
School and learning
Almost 70 per cent of girls with 47,XXX do fine at mainstream school, although most have
some 1:1 teaching, usually for reading, although they may
also need extra help in other subjects such as maths. The
need for support may be obvious in the early years and it
seems that if proper support is provided in the early years,
educational levels are maintained during adolescence (Otter
2009; Triple X syndrome group 2006).
The DIESC study found that 55 per cent of girls diagnosed
before birth or before their first birthday had no problems at
all at school. Of those diagnosed later (so more likely a
biased sample), eighteen per cent had no learning difficulties
at school.
Twelve years old
Most families say that their daughter enjoys school and
many girls particularly enjoy maths and spelling. Just over
30 per cent of girls diagnosed before birth had a statement
of special educational need but very few girls attended
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special units or schools. This suggests that any
difficulties they experience with learning are
relatively mild (DIESC 2009).
Overall, the DIESC study found that around 14 per
cent of girls whose 47,XXX was diagnosed before
birth or in the first year of life had a statement of
special educational needs. Of those diagnosed later,
50 per cent had a statement of special educational
needs.
Girls with triple X syndrome typically have slightly
more difficulty learning to read and write than usual.
1:1 teaching usually overcomes this difficulty and the
DIESC study found that girls showed relatively good
reading and writing skills.
However, there may be subtle differences. Girls with
triple X syndrome do seem to have particular
difficulties concentrating and paying attention but
they do not translate this difficulty into fidgeting or
hyperactivity. Rather, their concentration may easily
wander and they may have more difficulties than
expected seeing tasks through to a conclusion
(DIESC 2009; Tartaglia 2010).
Girls with triple X syndrome also often have difficulty
remembering what they have learned recently and
may need information repeated more times to fix it
in their memory (Triple X syndrome group 2006).
Graduation Day
- almost 70 per cent of girls
do fine at school
When girls with triple X syndrome have done intelligence tests, they have usually scored
around 20 points lower than others on verbal tests and around 15 points lower on
performance tests. Around 60 per cent of girls have an IQ over 90 but there’s a tendency
to do worse on verbal scores and only around 30 per cent of girls score over 90 on verbal
IQ tests. A difference of this size is common between brothers and sisters. But a girl with
triple X syndrome is likely to be aware that she struggles a little more with some aspects
of learning. This can affect her self-esteem but will generally improve once she leaves
school (Otter 2009).
School and friends
Girls with triple X syndrome are described by their families as very loving and kind. They
are caring, especially with animals and younger children. Many are described as having a
great sense of fun and most have close friends. Their social skills are generally within the
range expected for their age – they are aware of others, have good manners, cope with
change and are aware of danger with only slight differences between their behaviour and
their brothers and sisters. They also show good interpersonal skills, good understanding
of emotions and knowledge of how friendship works. But some parents have commented
that their daughter tends to smother others (DIESC 2009).
Some girls with triple X syndrome do find it difficult to make friends at school. This
difficulty can start early, in the pre-school years, and girls with triple X syndrome can
appear immature.
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The early
difficulties with
language may
underlie the
difficulties that
some girls face in
making friends.
They generally have
good relationships
with adults. But
11/25 girls aged 610 had problems
relating to other
Good interpersonal skills
children and 16
girls in this age group were unusually shy (Triple X
syndrome group 2006). They may lack self-confidence
because they know that they struggle a bit more to do
things that others do easily. But they appear to
Loving and kind
overcome these difficulties and are reported to be
popular and well-liked. All the same, in the DIESC study, a small group of parents
reported being worried about their daughter being bullied at school. Around age 11
appears to be a particularly difficult time for socialisation, as girls may still play in a way
that their peers might find childish. As they mature, their social skills improve as is also
suggested by better social skills in older girls, especially if diagnosed early in life (DIESC
2009; Otter 2009; Linden 2002; Bender 1995).
Meanwhile, families comment that stressing their daughter’s strengths (such as her
beautiful, long legs) helps their confidence.
Will growth be normal?
Typically, girls grow at a normal
rate until four years, then fast
until puberty. Some girls with
triple X syndrome grow more
rapidly than their classmates and
friends between four and eight
years, especially their legs. They
are typically in the top quarter of
girls for height. But any increase
in weight is less than in height, so
they are typically slim. They have
a delayed bone age until 7-10
years. These differences become
less obvious in adolescence
(Otter 2009).
Growing pains were reported by
12/20 families at a Unique study
day (Unique).
Long legs and slim: 6 years (left) and 12 years (right)
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Growing up:
up: 15 years (left); 17 years (centre left); 18 years (centre right and right)
Puberty and periods
Puberty usually starts around the time expected, with breasts developing from 11 years
(perhaps six months later than in other girls) and periods starting between 10-15 years.
Behaviour and mood
There’s a conflict of evidence over some
aspects of behaviour in girls and women
with triple X syndrome. The DIESC 2009
study found no evidence of greater
oppositional behaviours in girls with
47,XXX diagnosed early or before birth
compared to their sisters. The picture is
more complicated for anxiety: girls
diagnosed late were more anxious than
their sisters, and older girls more so than
younger girls, although few girls (whether
diagnosed early or late) scored above the
cut-off for clinical concern for anxiety.
Other researchers found that girls and
women with triple X syndrome can
become easily anxious, with social
avoidance, separation anxiety and
generalised anxiety figuring prominently.
Social immaturity relative to their peers is
also found which, together with their other
difficulties can make some girls
vulnerable to social pressures and
victimisation (Bender 1999; Tartaglia
2010). Some researchers have found high
numbers of women with depression
(Bender 1999; Harmon 1998).
There is a slightly increased incidence of
attention difficulties, attention deficit
disorder and conduct disorder (Robinson 1990; Pennington 1982).
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The DIESC study also found that girls with triple X syndrome were more likely to show
some behaviour and hyperactivity difficulties, but only 15 per cent of them scored at
levels that would cause any concern. Hyperactivity was only found in this study in the girls
who were diagnosed after their first birthday (that is, a biased group) and in this group
the difficulties did seem larger for older than for younger girls. They found that girls were
more prone than their siblings to difficult behaviour such as temper tantrums,
stubbornness and being easily led (DIESC 2009).
A number of studies have found that girls were particularly sensitive to stress in family
life. They needed parental support for longer than other girls (Otter 2009).
Psychological disorders have been shown to be more common in adulthood but respond
well to standard treatments (Otter 2009). This may be borne out by the findings of the
Triple X syndrome group who found that two adolescents/13 reported depression (Triple
X syndrome group 2006). Data from the DIESC study also showed that girls with triple X
syndrome are more likely than their sisters to be emotional (mood changes, temper
outbursts, frequent crying, many worries, often unhappy) and those diagnosed after their
first birthday (the biased group) also showed a tendency towards psychosomatic
difficulties, such as feeling tired all the time or complaining a lot about aches and pains.
Medication treatments are the same as for other girls and women but low starting doses
are recommended (Tartaglia 2010).
A Triple X syndrome group survey showed that 16/43 girls were shy when they started
nursery or first school. The survey also found that 10/25 girls aged 6-10 liked rituals or
disliked changes to their routine (Triple X syndrome group 2006).
Adulthood
Many women with triple X syndrome go on to further and higher education after school.
They go on to hold jobs at all levels in society. From what we know so far, many go on to
jobs of a practical and caring nature, including caring for children and older people.
There is some evidence of adults having problems in establishing satisfying relationships
and some women have continuing issues of low self-esteem (Otter 2009).
Having children
It seems that most women with triple X syndrome have no problem in becoming pregnant
and can expect to have healthy children, although no direct studies of fertility in triple X
syndrome have been carried out. The extra X chromosome is not usually passed on to
their children (Tartaglia 2010).
A woman with triple X syndrome can ask to be referred for genetic counselling before she
is pregnant. If she wants prenatal tests on her baby, they should also be offered.
However, the triple test and early pregnancy blood tests do not show whether a baby has
an extra sex chromosome, so an invasive test would be needed such as chorionic villus
sampling or an amniocentesis (where cells from the developing placenta or the fluid
around the baby are examined) (Otter 2009).
Early menopause
Premature ovarian failure (POF) seems to be somewhat more common than in the
general population. Cases have been described in the medical literature ranging in age
from 19 to 40 but no-one knows yet how common POF is in triple X syndrome. In a high
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percentage of the cases the woman with POF also has an autoimmune disorder (Otter
2009; Tartaglia 2010).
When this occurs, a woman in her 20s, 30s or early 40s starts having irregular periods
and may miss them altogether for a few months. The supply of eggs to the ovaries stops
before the expected age for menopause and the ovaries stop functioning normally. The
reason why this might happen in some women with triple X syndrome isn’t known for
certain but it’s theoretically possible that since half the eggs of a woman with triple X
syndrome would be expected to have an extra X chromosome they are perhaps sidelined.
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Notes on physical and clinical issues
Non-organic abdominal pains
A quarter of girls and young women experienced abdominal pains for which no
physical cause could be found (Otter 2009). This was confirmed in the Triple X syndrome
group survey, who found stomach pains reported by 14/43 families (Triple X syndrome
group 2006).
But the DIESC study threw a different light on this, finding that only the biased group, that
is, girls diagnosed after their first birthday had an increased tendency to complain about
aches and pains compared to their sisters. This wasn’t true for girls diagnosed earlier or
before birth (DIESC 2009).
Spinal curvature
A spinal curvature is probably more common among teenagers, especially hunching
forwards (Otter 2009). This has not been confirmed in the Triple X syndrome group survey
(Triple X syndrome group 2006). However, tall girls who are keen not to stand out are
known to stoop to conceal their height.
Constipation
A triple X syndrome group survey found that constipation was relatively common,
reported by 15/43 families with a daughter under 20 (Triple X syndrome group 2006).
Dental problems
Research into dental development in girls with triple X syndrome is sparse. A Unique
study day found that 14/20 families said their daughter had some sort of dental problem.
Problems described include poor enamel formation, pitting and need for fluoride coating
(Unique).
Urogenital tract
Genitourinary and kidney malformations may be slightly more common in girls with triple
X syndrome. It may make sense to scan the genitourinary tract with special attention
prenatally (Tartaglia 2010; Otter 2009). However, the Triple X syndrome survey found no
evidence of abnormalities in 43 girls diagnosed prenatally, although one had a membrane
over the vagina, one was born with a single kidney and one was prone to urine infections
(Triple X syndrome group 2006).
Seizures and abnormal EEGs
Some authors have suggested that in a minority of girls, unusual EEGs
(electroencephalograms - recordings of the brainwave patterns from the tiny electrical
signals from the brain) and seizures may be found. Treatment with anti-epileptic drugs
was effective (Otter 2009; Tartaglia 2010).
Brain imaging
Two small follow-up studies of women from the 1960s newborn groups found that their
brains were on average smaller than those of women without triple X syndrome. One of
the studies also found focuses of white matter in the brains of around a quarter of girls
and women with triple X syndrome. It’s unclear what this finding means (Tartaglia 2010).
Heart problems
Heart problems have been described, including holes between the upper or lower heart
chambers (atrial or ventricular septal defects), pulmonic stenosis (the entrance to the
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artery that takes blood to the lungs is unusually narrow) and aortic coarctation (the aorta
that takes the blood from the heart to the rest of the body is narrowed (Tartaglia 2010).
Screening and management of girls and women with Triple X syndrome
There is no general agreement among doctors as to whether girls and women with triple
X syndrome should have regular medical checks or not. Items in the schedule below were
suggested by Dr Maarten Otter (Otter 2009) and by Dr Nicole Tartaglia. Talking about
development and learning, Dr Tartaglia warns: ‘If present, developmental concerns and
educational struggles should be addressed aggressively instead of taking a ‘wait and see’
approach, since they are unlikely to improve or ‘catch up’ without targeted interventions
and delaying treatment will lead to poorer outcomes’ (Tartaglia 2010).
Prenatal
Focus on genitourinary tract while scanning
Neonatal
Normal paediatric screening
PrePre-school
EEG studies as indicated by medical history
Heart evaluation
Kidney ultrasound
Comprehensive developmental evaluation: examination by
developmental paediatrician or paediatric neurologist
focusing on language, social and motor development
Eye test
Speech and language screening
Investigation of learning needs
Family and individual support at home and at school
Primary school age
Repeat EEG if abnormalities found on pre-school EEG
Eye test
Hearing test
Social functioning test
Multidisciplinary assessment to identify strengths and
weaknesses and develop interventions and support
Educational and learning needs assessment
Family and individual support at home and at school
Secondary school age Social functioning test
Educational and learning needs assessment
Family and individual support at home and at school
School leavers
Physical examination if symptoms arise
Occupational investigation and support if necessary
Adults
Physical examination if symptoms arise
Psychological / psychiatric examination if symptoms arise
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Support and Information
Rare Chromosome Disorder Support Group,
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Tel/Fax: +44(0)1883 723356
info@rarechromo.org I www.rarechromo.org
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In the United Kingdom
Triple X syndrome Family Network Support Group
32 Francemary Road London SE4 1JS
+44 (0) 20 8690 9445 helenclements@hotmail.com
In the US
www.genetic.org
In the Netherlands
www.triple-x-syndroom.nl
Unique lists external message boards and websites in order to be helpful to families looking for
information and support. This does not imply that we endorse their content or have any
responsibility for it.
This information guide is not a substitute for personal medical advice. Families should
consult a medically qualified clinician in all matters relating to genetic diagnosis,
management and health. Information on genetic changes is a very fast-moving field
and while the information in this guide is believed to be the best available at the time of
publication, some facts may later change. Unique does its best to keep abreast of
changing information and to review its published guides as needed. The guide was
compiled by Unique and reviewed by Professor Maj Hultén, Professor of Reproductive
Genetics, University of Warwick and by Dr Gaia Scerif, Department of Experimental
Psychology, University of Oxford 2009. PM. Updated 5/2011; 11/2013 v2
Copyright
©
Unique 2013
Rare Chromosome Disorder Support Group Charity Number 1110661
Registered in England and Wales Company Number 5460413
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